HA Add-On: improve logging configuration

[s-allius]

Idea from @mime24 (see:#215 (comment))

...
just for completeness, we could develop following further steps:

variant log-files in mounted folder

we could give a option in configuration tab to configure the number of days to keep log-files.

variant debug-mode in Add-on Log

we could have a switch in add-on config that indicates the proxy to run in debug mode. this would plot debug messages to the Add-on (Supervisor) Logservice.
if we implement this as radio button/list option (Log-Level), we could also set it to a ERROR mode where the usual connect/disconnect messages doesn't appear.